Hello I always thought that the injector harness for speed density was the same as the one for mass air. The reason I thought this is because once I was told that all 87-88 speed density had sequential firing injectors even though they did not have mass air. On my F-150 it has speed density with batch firing injectors. I am going to convert both of my 87 GT's to mass air I already have the engine harness, but I need to know if I can use the 87 injector harness without doing a lot of wiring changes?